1. Field of the Invention
The present invention relates to a method of and an apparatus for melting a metal and injecting the melted metal into a mold or die in a die casting operation.
2. Prior Art
Die casting, per se, has been known since the mid-1800's. However, some aspects of the industry rely on tradition without considering new materials and knowledge.
In pressure die casting, two processes are generally used, namely, the hot chamber process and the cold chamber process.
In the hot chamber process, it has been traditional in the art to use a gooseneck type of apparatus, with a plunger arrangement suspended within a crucible, the plunger moving downward vertically to push molten metal through a passageway and out into a die.
In the cold chamber process, a piston is disposed horizontally in a bore having a hole in the top of the bore, forward of the piston. Molten metal is poured into the hole in the bore and the piston is, then, moved horizontally to force the molten metal into a die.
One drawback of the prior art is that no provision has been made for the casting of aluminum using the hot chamber process, which is generally more adaptable to high volume production, since it keeps a reservoir of molten metal within the apparatus at all times. Another disadvantage of the prior art equipment for the hot chamber process is that the gooseneck apparatus used is basically derived from Dusenbery's die casting machine which was invented in 1877, and no major re-thinking of the optimal type of machine has been done.
An overview of the history of pressure die casting and the two processes is given in Pressure Die Casting-Part 1 by B. Upton, published in 1982 by Pergamon press.
An example of prior art relating to a die casting machine is U.S. Pat. No. 4,356,858 issued to Perrella et al. In Perrella, a die casting system is disclosed in which a part is cast and trimmed without any lateral movement of the part. The apparatus as shown in FIG. 8A of Perrella is a variation on the traditional goose neck hot chamber design. A need exists, in the die casting art, for a method and apparatus which will enable aluminum parts to be die cast using a hot chamber process.